Progress on this project during 1976-77 is summarized as follows: (1) Antibody against aflatoxin B1 (Afla B1) was obtained 5-6 weeks after injection of bovine serum albumin (BSA)-Afla B1 conjugate into rabbits. The antibody has greatest binding efficiency for Afla B1, less for B2, G1, and Q1 and least for aflatoxicol, G2, and M1. Sterigmatocystin, coumarin and 4-Oh-coumarin did not give a cross reaction with the antibody. The sensitivity of the binding assay for detection of Afla B1 is in the range of 0.2 to 2.0 mg/0.5 ml sample. (2) Two approaches for radioimmunoassay (RIA) for Afla B1 and Ochratoxin A were tested. One involves the use of Millipore filter and the other involves the use of antibody-sepharose gel. Results show that the latter approach is more promising. (3) The possibility of modification of hepatotoxic effects of Afla B1 in the immunized rabbits was studied by challenging the rabbits with Afla B1 6 weeks after immunized with 250 ug of BSA-Afla B1. When rabbits were challenged with Afla B1 at a dose slightly less than the LD50 (0.3 mg/kg), all the immunized rabbits were protected from acute toxic effect. The overall results show that RIA for mycotoxins is simple, sensitive, and specific, and could be applied for the analysis of mycotoxins in foods and feeds.